Instant Access To 100,000+ Essays!

How do membranes and cell walls that surround cells control the movement of materials in and out of living cells? Relate membrane and wall structure to such processes as diffusion, osmosis, pinocytosis and phagocytosis. The surrounding cell walls and membranes can control the materials that pass in, out and through living cells. Four processes that can be related to this movement of materials are diffusion, osmosis, pinocytosis and phagocytosis. To perform their functions, cells must maintain an internal steady state in the midst of an ever-changing environment. This consistency, or ‘homeostasis’, is maintained in part by the regulation of the movement of materials in and out of the cell. To achieve this control, a cell is bounded by a delicate membrane, which can distinguish between substances, slowing down or stopping the movement of some while allowing others to pass through freely. Because not all substances penetrate the cell membrane equally well, the membrane is known as being ‘differentially’, or ‘selectively permeable’. Cell walls and membrane The main purpose of the cell membrane is to regulate the movement of materials in and out of the cell. By doing so, the cell’s internal environment can di